The present invention relates to a thermoplastic interpolymer product comprising an xcex1-olefin interpolymerized with at least one vinyl or vinylidene aromatic monomer and/or at least one hindered aliphatic or cycloaliphatic vinyl or vinylidene aromatic monomer and, in at least one aspect, is characterized as having substantially synergistic thermal properties. The invention also relates to a process for manufacturing the interpolymer product wherein the process comprises employing two or more single site catalyst systems in at least one reaction environment (or reactor) and wherein at least two of the catalyst systems have (a) different monomer incorporation capabilities or reactivities and (b) the same or, optionally, different monomer sequencing and/or tacticity characteristics. With unique thermal property attributes, the interpolymer product is useful, for example, for impact, bitumen and asphalt modification, adhesives, dispersions or latexes and fabricated articles such as, but not limited to, foams, films, sheet, moldings, thermoforms, profiles and fibers.
The generic class of materials covered by xcex1-olefin/vinyl or vinylidene aromatic and/or hindered aliphatic or cycloaliphatic vinyl or vinylidene interpolymers and including materials such as substantially random xcex1-olefin/vinyl aromatic interpolymers are known in the art and offer a range of material structures and properties which makes them useful in various applications. For example, U.S. Pat. No. 5,460,818, the disclosure of which is incorporated herein by reference, describes substantially random xcex1-olefin/vinyl aromatic monomer interpolymers as compatibilizers for blends of polyethylene and polystyrene. However, known methods and procedures for manufacturing xcex1-olefin/vinyl or vinylidene aromatic and/or hindered aliphatic or cycloaliphatic vinyl or vinylidene interpolymers do not provide independent control of material properties and attributes. That is, crystallinity, melting point and glass transition characteristics are known to inevitably vary with comonomer concentration where increase concentrations result in lower crystallinities, melting point temperatures, glass transition temperatures and service temperatures.
There are several known methods for preparing xcex1-olefin/vinyl or vinylidene aromatic and/or hindered aliphatic or cycloaliphatic vinyl or vinylidene interpolymers such as those described by Francis J. Timmers et al. in U.S. application Ser. No. 08/708,869, filed Sep. 4, 1996 (now abandoned); John G. Bradfute et al. (W. R. Grace and Co.) in WO 95/32095; R. B. Pannell (Exxon Chemical Patents, inc.) in WO 94/00500; and in Plastics Technology, p. 25 (September 1992), the disclosures of which are incorporated herein by reference.
Numerous other preparative methods for xcex1-olefin/vinyl or vinylidene aromatic and/or hindered aliphatic or cycloaliphatic vinyl or vinylidene interpolymers have been described in the literature. For example, Longo and Grassi (Makromol. Chem., Volume 191, pages 2387 to 2396 [1990]) and D""Anniello et al. (Journal of Applied Polymer Science, Volume 58, pages 1701-1706 [1995]), the disclosures of which are incorporated herein by reference, reported the use of a catalytic system based on methylalumoxane (MAO) and cyclopentadienyltitanium trichloride (CpTiCl3) to prepare an ethylene-styrene copolymer. Xu and Lin (Polymer Preprints, Am. Chem. Soc., Div. Polym. Chem., Volume 35, pages 686,687 [1994]), the disclosure of which is incorporated herein by reference, have reported copolymerization using a MgCl2/TiCl4/NdCl3/Al(iBu)3 catalyst to give random copolymers of styrene and propylene. Lu et al. (Journal of Applied Polymer Science, Volume 53, pages 1453 to 1460 [1994]), the disclosure of which is incorporated herein by reference, have described the copolymerization of ethylene and styrene using a Ticl4/NdCl3/MgCl2/al(Et)3 catalyst. Sernetz and Mulhaupt, (Macromol. Chem. Phys., V. 197, pp. 1071-1083, 1997), the disclosure of which is incorporated herein by reference, have described the influence of polymerization conditions on the copolymerization of styrene with ethylene using Me2Si(Me4Cp)(n-tert-butyl)TiCl2/Methylaluminoxane Ziegler-Natta catalysts. Copolymers of ethylene and styrene produced by bridged metallocene catalysts have been described by Arai, Toshiaki and Suzuki (Polymer Preprints, Am. Chem. Soc., Div. Polym. Chem., Volume 38, pages 349, 350 [1997]), the disclosure of which is incorporated herein by reference. Also, random copolymers of ethylene and styrene having high isotacticity are disclosed in Polymer Preprints, Vol. 39, no. 1, March 1998 by Toru Aria et al., the disclosure of which is incorporated herein by reference.
Also several patent describe the manufacture of xcex1-olefin/vinyl aromatic monomer interpolymers such as propylene/styrene and butene/styrene in U.S. Pat. No. 5,244,996, issued to Mitsui Petrochemical Industries Ltd.; U.S. Pat. No. 5,652,315, also issued to Mitsui Petrochemical Industries Ltd.; or DE 197 11 339 A1 to Denki Kagaku Kogyo KK, the disclosures of all three of which are incorporated herein by reference. Ethylene/styrene copolymer produced by bridged metallocene catalysts are also described in U.S. Pat. No. 5,652,315, issued to Mitsui Toatsu Chemicals, Inc.
Pseudo-random ethylene/vinyl aromatic interpolymers and the catalyst systems for making the same are disclosed in U.S. Pat. No. 5,703,187 and EP 416 815 A2, the disclosures of which are incorporated herein by reference.
U.S. patent application Ser. No. 08/991,836, filed Dec. 16, 1997 (now abandoned) and WO 98/10018, the disclosures of both of which are incorporated herein, in their entireties, by reference, indicate that a suitable method for manufacturing substantially random ethylene/vinyl aromatic interpolymers involves polymerizing a mixture of polymerizable monomers in the presence of one or more metallocene or constrained geometry catalysts in combination with various cocatalysts. However, the exemplified compositions therein all involve the same single catalyst composition of a titanium-based constrained geometry catalyst together with tris(pentafluorophenyl)boron as the activator and methylaluminoxane as the cocatalyst. That is, all reported examples were monocatalyzed interpolymers. Furthermore, there is no explicit disclosure in these descriptions that interpolymer made using multiple catalyst systems can provide improved thermal properties such as substantially higher meting points at substantially comparable crystallinities or diffused Tg responses.
Blends comprising xcex1-olefin/vinylidene aromatic monomer and/or hindered aliphatic or cycloaliphatic vinylidene monomer interpolymers are described in WO 95/27755, in the names of Chung P. Park et al. and WO 98/10018, in the names of Martin J. Guest et al., the disclosures of which are incorporated herein by reference. All of the exemplified compositions consisted of physical melt blend preparations using component interpolymers made from a single catalyst composition. That is, the blends were not made using an in-situ or multiple reactor interpolymerization technique, nor were they manufactured using multiple catalyst compositions and, as such, all component polymers were monocatalyzed.
Moreover, melt blending is not known to provide independent or unique control of thermal resistance, melting behavior and glass transition characteristics as no complete data of such attributes are reported in WO 95/27755 nor WO 98/10018. Thus it remains, although known xcex1-olefin/vinyl or vinylidene aromatic interpolymers have several important attributes, they also exhibit several important deficiencies. For example, known xcex1-olefin/vinyl or vinylidene aromatic interpolymer compositions, whether monocatalyzed or the melt blends, are characterized as having relatively low maximum service temperatures and narrow glass transition temperature ranges or widths (i.e. less than 15xc2x0 C.) which limit their usefulness for elevated temperature service/applications as well as for applications which require the effective glass transition to span across a broad temperatures range. It is an object of the present invention to solve the problem of deficient thermal characteristics exhibited by known xcex1-olefin/vinyl or vinylidene aromatic interpolymers.
We have discovered a new family of xcex1-olefin/vinyl aromatic interpolymer products which are characterized as having substantially synergistic and improved thermal characteristics. The broad aspect of the invention is an interpolymer product comprising an xcex1-olefin interpolymerized with at least one vinyl or vinylidene aromatic monomer wherein the interpolymer product is characterized as having:
A1) a melting point, as determined using differential scanning calorimetry, equal to or greater than the product of the equation:
xe2x80x83melting point=128xe2x88x921.3333xc3x97total weight percent interpolymerized vinyl and/or vinylidene aromatic monomer,
preferably, equal to or greater than the product of the equation:
melting point=144xe2x88x921.53xc3x97total weight percent interpolymerized vinyl and/or vinylidene aromatic monomer,
more preferably, equal to or greater than the product of the equation:
melting point=160xe2x88x921.66667xc3x97total weight percent interpolymerized vinyl and/or vinylidene aromatic monomer,
xe2x80x83or
A2) a highest peak melting point temperature (as determined using differential scanning calorimetry (DSC)) or a maximum service temperature (as determined using thermal mechanical analysis (TMA)) equal to or greater than 16 percent, preferably 30 percent, more preferably 50 percent higher than the melting point or maximum service temperature of a CAT2 monocatalyzed substantially random xcex1-olefin/vinyl or vinylidene aromatic monomer interpolymer having an equivalent total mol percent interpolymerized vinyl and/or vinylidene aromatic monomer concentration, or
B) a glass transition temperature range or width at half peak temperature height of greater than or equal to 15xc2x0 C., preferably greater than or equal to 20xc2x0 C., more preferably greater than or equal to 25xc2x0 C., most preferably greater than or equal to 30xc2x0 C., as determined using dynamic mechanical spectroscopy (DMS) loss modulus (Gxe2x80x3) data.
In a preferred embodiment, the inventive interpolymer product comprises ethylene as the xcex1-olefin and styrene as the at least one vinyl or vinylidene aromatic monomer and is characterized as having:
A) a highest peak melting point temperature (as determined using differential scanning calorimetry (DSC)) or a maximum service temperature (as determined using thermal mechanical analysis (TMA)) equal to or greater than 16 percent, preferably 30 percent, more preferably 50 percent higher than the melting point or maximum service temperature of a CAT2 monocatalyzed substantially random ethylene/styrene interpolymer having an equivalent total mol percent interpolymerized vinyl and/or vinylidene concentration, or
B) a glass transition temperature range or width at half peak temperature height of greater than or equal to 15xc2x0 C., preferably greater than or equal to 20xc2x0 C., more preferably greater than or equal to 25xc2x0 C., most preferably greater than or equal to 30xc2x0 C., as determined using dynamic mechanical spectroscopy (DMS) loss modulus (Gxe2x80x3) data.
In other embodiments, the interpolymer product is dominantly substantially random, random, or alternating (i.e. more than 50 weight percent of the product is characterized as having the particular sequence). Preferably, the product is more than 70 weight percent, more preferably more than 80 weight percent and most preferably more than 90 weight percent substantially random. In especially preferred embodiments, the interpolymer product is substantially random with respect to all incorporated vinyl or vinylidene aromatic monomer sequences of more than three units.
In other embodiments, the interpolymer product can be partially substantially random, random, alternately, diadic, triadic, tetradic or any combination thereof. That is, the interpolymer product can be variably incorporated and optionally variably sequenced. For example, the interpolymer product can be variably incorporated and dominantly substantially random where the two catalyst systems (e.g. CAT1 and CAT2) employed both characteristically provide a substantially random monomer sequencing. Such is believed to be the case as to incorporation even where the incorporation ratio between the two catalyst systems is 50/50. The interpolymer product can be variably incorporated and variably sequenced where, for example, the two catalyst systems employed both characteristically provide a different monomer sequence.
In still other embodiments, the inventive interpolymer product can be variably incorporated and optionally variably sequenced and/or variably atactic, isotactic, syndiotactic or a combination thereof. That is, the inventive interpolymer product can have a mixed, the same or a different tacticity (i.e. atactic, isotactic, syndiotactic or combinations thereof with respect to any partial or total sequence variety. Of particular interest (especially for elastic article applications) is an embodiment where the interpolymer product has improved thermal property attributes and comprises random, substantially random or alternating (or any combination thereof hard and soft segments or blocks.
Where the interpolymer has a high degree of alternating monomer sequencing (i.e. the interpolymer gives peaks at all three chemical shift regions of the main chain methylene and methyne carbons and the peak areas of these regions is not less than 70 percent of the total peak area of the main chain methylene and methyne carbons), a high degree of isotacticity (i.e. the isotactic diad is not less than 0.55) is most preferred
Another aspect of the invention is an interpolymer product comprising xcex1-olefin and at least one vinyl or vinylidene aromatic monomer made using at least two single site catalyst systems in at least one reaction environment or reactor wherein the catalyst systems are selected and operated to provide different monomer incorporation capabilities or reactivities.
A third aspect of the invention is a process for making an interpolymer product, the product comprising an xcex1-olefin interpolymerized with at least one vinyl or vinylidene aromatic monomer, the process comprising
a) selecting at least two single site catalyst systems,
b) feeding the catalysts systems to at least one reaction environment or reactor, and
c) controlling the reaction environment (or reactor), catalyst systems and interpolymerization conditions such that the catalyst systems operate or function at different vinyl or vinylidene aromatic monomer incorporation capabilities or interpolymerization reactivity rates.
In certain aspects, the inventive interpolymer product has surprisingly improved thermal properties. For example, thermal property attributes can be controlled independent of monomer concentration and substantially independent of crystallinity or glass transition peak temperature. In particular aspects, as unique features, the melting point and/or thermal resistance of the inventive interpolymer product is substantially higher than that of a comparative substantially random interpolymer having an equivalent vinyl or vinylidene aromatic concentration and/or substantially comparably crystallinity. Alternatively, in other aspects and when amorphous, the inventive interpolymer product is surprisingly characterized by a more diffuse (i.e. broader) Tg temperature range or width at equivalent vinyl or vinylidene aromatic concentration.
In particular embodiments, the inventive interpolymer product is characterized by various physical property enhancements such as, but not limited to, improved processability in terms of shear thinning and melt strength improvement from molecular weight control; improved mechanical properties such as impact resistance and tensile elongation; improved control of stress relaxation and elastic recovery attributes; improved control of surface characteristics for enhancement such as paintability; and combinations thereof.
The commercial benefit of the present invention is now xcex1-olefin/vinyl or vinylidene aromatic interpolymers with improved thermal characteristics are available. With improvements such as, for example, significantly higher maximum service temperatures, it now possible to provide elastic articles (e.g. waist bands in undergarments) which retain their elastic properties after exposure to elevated temperatures such as laundry dryers.